text: /*****************************************************************************
  * ppp.h - Network Point to Point Protocol header file.
  *
  * Copyright (c) 2003 by Marc Boucher, Services Informatiques (MBSI) inc.
  * portions Copyright (c) 1997 Global Election Systems Inc.
  *
  * The authors hereby grant permission to use, copy, modify, distribute,
  * and license this software and its documentation for any purpose, provided
  * that existing copyright notices are retained in all copies and that this
  * notice and the following disclaimer are included verbatim in any 
  * distributions. No written agreement, license, or royalty fee is required
  * for any of the authorized uses.
  *
  * THIS SOFTWARE IS PROVIDED BY THE CONTRIBUTORS *AS IS* AND ANY EXPRESS OR
  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 
  * IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
  ******************************************************************************
  * REVISION HISTORY
  *
  * 03-01-01 Marc Boucher <marc@mbsi.ca>
  *   Ported to lwIP.
  * 97-11-05 Guy Lancaster <glanca@gesn.com>, Global Election Systems Inc.
  *   Original derived from BSD codes.
  *****************************************************************************/
  
  #include "netif/ppp/ppp_opts.h"
  #if PPP_SUPPORT /* don't build if not configured for use in lwipopts.h */
  
  #ifndef PPP_H
  #define PPP_H
  
  #include "lwip/def.h"
  #include "lwip/stats.h"
  #include "lwip/mem.h"
  #include "lwip/netif.h"
  #include "lwip/sys.h"
  #include "lwip/timeouts.h"
  #if PPP_IPV6_SUPPORT
  #include "lwip/ip6_addr.h"
  #endif /* PPP_IPV6_SUPPORT */
  
  #ifdef __cplusplus
  extern "C" {
  #endif
  
  /* Disable non-working or rarely used PPP feature, so rarely that we don't want to bloat ppp_opts.h with them */
  #ifndef PPP_OPTIONS
  #define PPP_OPTIONS         0
  #endif
  
  #ifndef PPP_NOTIFY
  #define PPP_NOTIFY          0
  #endif
  
  #ifndef PPP_REMOTENAME
  #define PPP_REMOTENAME      0
  #endif
  
  #ifndef PPP_IDLETIMELIMIT
  #define PPP_IDLETIMELIMIT   0
  #endif
  
  #ifndef PPP_LCP_ADAPTIVE
  #define PPP_LCP_ADAPTIVE    0
  #endif
  
  #ifndef PPP_MAXCONNECT
  #define PPP_MAXCONNECT      0
  #endif
  
  #ifndef PPP_ALLOWED_ADDRS
  #define PPP_ALLOWED_ADDRS   0
  #endif
  
  #ifndef PPP_PROTOCOLNAME
  #define PPP_PROTOCOLNAME    0
  #endif
  
  #ifndef PPP_STATS_SUPPORT
  #define PPP_STATS_SUPPORT   0
  #endif
  
  #ifndef DEFLATE_SUPPORT
  #define DEFLATE_SUPPORT     0
  #endif
  
  #ifndef BSDCOMPRESS_SUPPORT
  #define BSDCOMPRESS_SUPPORT 0
  #endif
  
  #ifndef PREDICTOR_SUPPORT
  #define PREDICTOR_SUPPORT   0
  #endif
  
  /*************************
  *** PUBLIC DEFINITIONS ***
  *************************/
  
  /*
   * The basic PPP frame.
   */
  #define PPP_HDRLEN	4	/* octets for standard ppp header */
  #define PPP_FCSLEN	2	/* octets for FCS */
  
  /*
   * Values for phase.
   */
  #define PPP_PHASE_DEAD          0
  #define PPP_PHASE_MASTER        1
  #define PPP_PHASE_HOLDOFF       2
  #define PPP_PHASE_INITIALIZE    3
  #define PPP_PHASE_SERIALCONN    4
  #define PPP_PHASE_DORMANT       5
  #define PPP_PHASE_ESTABLISH     6
  #define PPP_PHASE_AUTHENTICATE  7
  #define PPP_PHASE_CALLBACK      8
  #define PPP_PHASE_NETWORK       9
  #define PPP_PHASE_RUNNING       10
  #define PPP_PHASE_TERMINATE     11
  #define PPP_PHASE_DISCONNECT    12
  
  /* Error codes. */
  #define PPPERR_NONE         0  /* No error. */
  #define PPPERR_PARAM        1  /* Invalid parameter. */
  #define PPPERR_OPEN         2  /* Unable to open PPP session. */
  #define PPPERR_DEVICE       3  /* Invalid I/O device for PPP. */
  #define PPPERR_ALLOC        4  /* Unable to allocate resources. */
  #define PPPERR_USER         5  /* User interrupt. */
  #define PPPERR_CONNECT      6  /* Connection lost. */
  #define PPPERR_AUTHFAIL     7  /* Failed authentication challenge. */
  #define PPPERR_PROTOCOL     8  /* Failed to meet protocol. */
  #define PPPERR_PEERDEAD     9  /* Connection timeout */
  #define PPPERR_IDLETIMEOUT  10 /* Idle Timeout */
  #define PPPERR_CONNECTTIME  11 /* Max connect time reached */
  #define PPPERR_LOOPBACK     12 /* Loopback detected */
  
  /* Whether auth support is enabled at all */
  #define PPP_AUTH_SUPPORT (PAP_SUPPORT || CHAP_SUPPORT || EAP_SUPPORT)
  
  /************************
  *** PUBLIC DATA TYPES ***
  ************************/
  
  /*
   * Other headers require ppp_pcb definition for prototypes, but ppp_pcb
   * require some structure definition from other headers as well, we are
   * fixing the dependency loop here by declaring the ppp_pcb type then
   * by including headers containing necessary struct definition for ppp_pcb
   */
  typedef struct ppp_pcb_s ppp_pcb;
  
  /* Type definitions for BSD code. */
  #ifndef __u_char_defined
  typedef unsigned long  u_long;
  typedef unsigned int   u_int;
  typedef unsigned short u_short;
  typedef unsigned char  u_char;
  #endif
  
  #include "fsm.h"
  #include "lcp.h"
  #if CCP_SUPPORT
  #include "ccp.h"
  #endif /* CCP_SUPPORT */
  #if MPPE_SUPPORT
  #include "mppe.h"
  #endif /* MPPE_SUPPORT */
  #if PPP_IPV4_SUPPORT
  #include "ipcp.h"
  #endif /* PPP_IPV4_SUPPORT */
  #if PPP_IPV6_SUPPORT
  #include "ipv6cp.h"
  #endif /* PPP_IPV6_SUPPORT */
  #if PAP_SUPPORT
  #include "upap.h"
  #endif /* PAP_SUPPORT */
  #if CHAP_SUPPORT
  #include "chap-new.h"
  #endif /* CHAP_SUPPORT */
  #if EAP_SUPPORT
  #include "eap.h"
  #endif /* EAP_SUPPORT */
  #if VJ_SUPPORT
  #include "vj.h"
  #endif /* VJ_SUPPORT */
  
  /* Link status callback function prototype */
  typedef void (*ppp_link_status_cb_fn)(ppp_pcb *pcb, int err_code, void *ctx);
  
  /*
   * PPP configuration.
   */
  typedef struct ppp_settings_s {
  
  #if PPP_SERVER && PPP_AUTH_SUPPORT
    unsigned int  auth_required       :1;      /* Peer is required to authenticate */
    unsigned int  null_login          :1;      /* Username of "" and a password of "" are acceptable */
  #endif /* PPP_SERVER && PPP_AUTH_SUPPORT */
  #if PPP_REMOTENAME
    unsigned int  explicit_remote     :1;      /* remote_name specified with remotename opt */
  #endif /* PPP_REMOTENAME */
  #if PAP_SUPPORT
    unsigned int  refuse_pap          :1;      /* Don't proceed auth. with PAP */
  #endif /* PAP_SUPPORT */
  #if CHAP_SUPPORT
    unsigned int  refuse_chap         :1;      /* Don't proceed auth. with CHAP */
  #endif /* CHAP_SUPPORT */
  #if MSCHAP_SUPPORT
    unsigned int  refuse_mschap       :1;      /* Don't proceed auth. with MS-CHAP */
    unsigned int  refuse_mschap_v2    :1;      /* Don't proceed auth. with MS-CHAPv2 */
  #endif /* MSCHAP_SUPPORT */
  #if EAP_SUPPORT
    unsigned int  refuse_eap          :1;      /* Don't proceed auth. with EAP */
  #endif /* EAP_SUPPORT */
  #if LWIP_DNS
    unsigned int  usepeerdns          :1;      /* Ask peer for DNS adds */
  #endif /* LWIP_DNS */
    unsigned int  persist             :1;      /* Persist mode, always try to open the connection */
  #if PRINTPKT_SUPPORT
    unsigned int  hide_password       :1;      /* Hide password in dumped packets */
  #endif /* PRINTPKT_SUPPORT */
    unsigned int  noremoteip          :1;      /* Let him have no IP address */
    unsigned int  lax_recv            :1;      /* accept control chars in asyncmap */
    unsigned int  noendpoint          :1;      /* don't send/accept endpoint discriminator */
  #if PPP_LCP_ADAPTIVE
    unsigned int lcp_echo_adaptive    :1;      /* request echo only if the link was idle */
  #endif /* PPP_LCP_ADAPTIVE */
  #if MPPE_SUPPORT
    unsigned int require_mppe         :1;      /* Require MPPE (Microsoft Point to Point Encryption) */
    unsigned int refuse_mppe_40       :1;      /* Allow MPPE 40-bit mode? */
    unsigned int refuse_mppe_128      :1;      /* Allow MPPE 128-bit mode? */
    unsigned int refuse_mppe_stateful :1;      /* Allow MPPE stateful mode? */
  #endif /* MPPE_SUPPORT */
  
    u16_t  listen_time;                 /* time to listen first (ms), waiting for peer to send LCP packet */
  
  #if PPP_IDLETIMELIMIT
    u16_t  idle_time_limit;             /* Disconnect if idle for this many seconds */
  #endif /* PPP_IDLETIMELIMIT */
  #if PPP_MAXCONNECT
    u32_t  maxconnect;                  /* Maximum connect time (seconds) */
  #endif /* PPP_MAXCONNECT */
  
  #if PPP_AUTH_SUPPORT
    /* auth data */
    const char  *user;                   /* Username for PAP */
    const char  *passwd;                 /* Password for PAP, secret for CHAP */
  #if PPP_REMOTENAME
    char  remote_name[MAXNAMELEN   + 1]; /* Peer's name for authentication */
  #endif /* PPP_REMOTENAME */
  
  #if PAP_SUPPORT
    u8_t  pap_timeout_time;        /* Timeout (seconds) for auth-req retrans. */
    u8_t  pap_max_transmits;       /* Number of auth-reqs sent */
  #if PPP_SERVER
    u8_t  pap_req_timeout;         /* Time to wait for auth-req from peer */
  #endif /* PPP_SERVER */
  #endif /* PAP_SUPPPORT */
  
  #if CHAP_SUPPORT
    u8_t  chap_timeout_time;       /* Timeout (seconds) for retransmitting req */
    u8_t  chap_max_transmits;      /* max # times to send challenge */
  #if PPP_SERVER
    u8_t  chap_rechallenge_time;   /* Time to wait for auth-req from peer */
  #endif /* PPP_SERVER */
  #endif /* CHAP_SUPPPORT */
  
  #if EAP_SUPPORT
    u8_t  eap_req_time;            /* Time to wait (for retransmit/fail) */
    u8_t  eap_allow_req;           /* Max Requests allowed */
  #if PPP_SERVER
    u8_t  eap_timeout_time;        /* Time to wait (for retransmit/fail) */
    u8_t  eap_max_transmits;       /* Max Requests allowed */
  #endif /* PPP_SERVER */
  #endif /* EAP_SUPPORT */
  
  #endif /* PPP_AUTH_SUPPORT */
  
    u8_t  fsm_timeout_time;            /* Timeout time in seconds */
    u8_t  fsm_max_conf_req_transmits;  /* Maximum Configure-Request transmissions */
    u8_t  fsm_max_term_transmits;      /* Maximum Terminate-Request transmissions */
    u8_t  fsm_max_nak_loops;           /* Maximum number of nak loops tolerated */
  
    u8_t  lcp_loopbackfail;     /* Number of times we receive our magic number from the peer
                                   before deciding the link is looped-back. */
    u8_t  lcp_echo_interval;    /* Interval between LCP echo-requests */
    u8_t  lcp_echo_fails;       /* Tolerance to unanswered echo-requests */
  
  } ppp_settings;
  
  #if PPP_SERVER
  struct ppp_addrs {
  #if PPP_IPV4_SUPPORT
    ip4_addr_t our_ipaddr, his_ipaddr, netmask;
  #if LWIP_DNS
    ip4_addr_t dns1, dns2;
  #endif /* LWIP_DNS */
  #endif /* PPP_IPV4_SUPPORT */
  #if PPP_IPV6_SUPPORT
    ip6_addr_t our6_ipaddr, his6_ipaddr;
  #endif /* PPP_IPV6_SUPPORT */
  };
  #endif /* PPP_SERVER */
  
  /*
   * PPP interface control block.
   */
  struct ppp_pcb_s {
    ppp_settings settings;
    const struct link_callbacks *link_cb;
    void *link_ctx_cb;
    void (*link_status_cb)(ppp_pcb *pcb, int err_code, void *ctx);  /* Status change callback */
  #if PPP_NOTIFY_PHASE
    void (*notify_phase_cb)(ppp_pcb *pcb, u8_t phase, void *ctx);   /* Notify phase callback */
  #endif /* PPP_NOTIFY_PHASE */
    void *ctx_cb;                  /* Callbacks optional pointer */
    struct netif *netif;           /* PPP interface */
    u8_t phase;                    /* where the link is at */
    u8_t err_code;                 /* Code indicating why interface is down. */
  
    /* flags */
  #if PPP_IPV4_SUPPORT
    unsigned int ask_for_local           :1; /* request our address from peer */
    unsigned int ipcp_is_open            :1; /* haven't called np_finished() */
    unsigned int ipcp_is_up              :1; /* have called ipcp_up() */
    unsigned int if4_up                  :1; /* True when the IPv4 interface is up. */
  #if 0 /* UNUSED - PROXY ARP */
    unsigned int proxy_arp_set           :1; /* Have created proxy arp entry */
  #endif /* UNUSED - PROXY ARP */
  #endif /* PPP_IPV4_SUPPORT */
  #if PPP_IPV6_SUPPORT
    unsigned int ipv6cp_is_up            :1; /* have called ip6cp_up() */
    unsigned int if6_up                  :1; /* True when the IPv6 interface is up. */
  #endif /* PPP_IPV6_SUPPORT */
    unsigned int lcp_echo_timer_running  :1; /* set if a timer is running */
  #if VJ_SUPPORT
    unsigned int vj_enabled              :1; /* Flag indicating VJ compression enabled. */
  #endif /* VJ_SUPPORT */
  #if CCP_SUPPORT
    unsigned int ccp_all_rejected        :1; /* we rejected all peer's options */
  #endif /* CCP_SUPPORT */
  #if MPPE_SUPPORT
    unsigned int mppe_keys_set           :1; /* Have the MPPE keys been set? */
  #endif /* MPPE_SUPPORT */
  
  #if PPP_AUTH_SUPPORT
    /* auth data */
  #if PPP_SERVER && defined(HAVE_MULTILINK)
    char peer_authname[MAXNAMELEN + 1]; /* The name by which the peer authenticated itself to us. */
  #endif /* PPP_SERVER && defined(HAVE_MULTILINK) */
    u16_t auth_pending;        /* Records which authentication operations haven't completed yet. */
    u16_t auth_done;           /* Records which authentication operations have been completed. */
  
  #if PAP_SUPPORT
    upap_state upap;           /* PAP data */
  #endif /* PAP_SUPPORT */
  
  #if CHAP_SUPPORT
    chap_client_state chap_client;  /* CHAP client data */
  #if PPP_SERVER
    chap_server_state chap_server;  /* CHAP server data */
  #endif /* PPP_SERVER */
  #endif /* CHAP_SUPPORT */
  
  #if EAP_SUPPORT
    eap_state eap;            /* EAP data */
  #endif /* EAP_SUPPORT */
  #endif /* PPP_AUTH_SUPPORT */
  
    fsm lcp_fsm;                   /* LCP fsm structure */
    lcp_options lcp_wantoptions;   /* Options that we want to request */
    lcp_options lcp_gotoptions;    /* Options that peer ack'd */
    lcp_options lcp_allowoptions;  /* Options we allow peer to request */
    lcp_options lcp_hisoptions;    /* Options that we ack'd */
    u16_t peer_mru;                /* currently negotiated peer MRU */
    u8_t lcp_echos_pending;        /* Number of outstanding echo msgs */
    u8_t lcp_echo_number;          /* ID number of next echo frame */
  
    u8_t num_np_open;              /* Number of network protocols which we have opened. */
    u8_t num_np_up;                /* Number of network protocols which have come up. */
  
  #if VJ_SUPPORT
    struct vjcompress vj_comp;     /* Van Jacobson compression header. */
  #endif /* VJ_SUPPORT */
  
  #if CCP_SUPPORT
    fsm ccp_fsm;                   /* CCP fsm structure */
    ccp_options ccp_wantoptions;   /* what to request the peer to use */
    ccp_options ccp_gotoptions;    /* what the peer agreed to do */
    ccp_options ccp_allowoptions;  /* what we'll agree to do */
    ccp_options ccp_hisoptions;    /* what we agreed to do */
    u8_t ccp_localstate;           /* Local state (mainly for handling reset-reqs and reset-acks). */
    u8_t ccp_receive_method;       /* Method chosen on receive path */
    u8_t ccp_transmit_method;      /* Method chosen on transmit path */
  #if MPPE_SUPPORT
    ppp_mppe_state mppe_comp;      /* MPPE "compressor" structure */
    ppp_mppe_state mppe_decomp;    /* MPPE "decompressor" structure */
  #endif /* MPPE_SUPPORT */
  #endif /* CCP_SUPPORT */
  
  #if PPP_IPV4_SUPPORT
    fsm ipcp_fsm;                   /* IPCP fsm structure */
    ipcp_options ipcp_wantoptions;  /* Options that we want to request */
    ipcp_options ipcp_gotoptions;   /* Options that peer ack'd */
    ipcp_options ipcp_allowoptions; /* Options we allow peer to request */
    ipcp_options ipcp_hisoptions;   /* Options that we ack'd */
  #endif /* PPP_IPV4_SUPPORT */
  
  #if PPP_IPV6_SUPPORT
    fsm ipv6cp_fsm;                     /* IPV6CP fsm structure */
    ipv6cp_options ipv6cp_wantoptions;  /* Options that we want to request */
    ipv6cp_options ipv6cp_gotoptions;   /* Options that peer ack'd */
    ipv6cp_options ipv6cp_allowoptions; /* Options we allow peer to request */
    ipv6cp_options ipv6cp_hisoptions;   /* Options that we ack'd */
  #endif /* PPP_IPV6_SUPPORT */
  };
  
  /************************
   *** PUBLIC FUNCTIONS ***
   ************************/
  
  /*
   * WARNING: For multi-threads environment, all ppp_set_* functions most
   * only be called while the PPP is in the dead phase (i.e. disconnected).
   */
  
  #if PPP_AUTH_SUPPORT
  /*
   * Set PPP authentication.
   *
   * Warning: Using PPPAUTHTYPE_ANY might have security consequences.
   * RFC 1994 says:
   *
   * In practice, within or associated with each PPP server, there is a
   * database which associates "user" names with authentication
   * information ("secrets").  It is not anticipated that a particular
   * named user would be authenticated by multiple methods.  This would
   * make the user vulnerable to attacks which negotiate the least secure
   * method from among a set (such as PAP rather than CHAP).  If the same
   * secret was used, PAP would reveal the secret to be used later with
   * CHAP.
   *
   * Instead, for each user name there should be an indication of exactly
   * one method used to authenticate that user name.  If a user needs to
   * make use of different authentication methods under different
   * circumstances, then distinct user names SHOULD be employed, each of
   * which identifies exactly one authentication method.
   *
   * Default is none auth type, unset (NULL) user and passwd.
   */
  #define PPPAUTHTYPE_NONE      0x00
  #define PPPAUTHTYPE_PAP       0x01
  #define PPPAUTHTYPE_CHAP      0x02
  #define PPPAUTHTYPE_MSCHAP    0x04
  #define PPPAUTHTYPE_MSCHAP_V2 0x08
  #define PPPAUTHTYPE_EAP       0x10
  #define PPPAUTHTYPE_ANY       0xff
  void ppp_set_auth(ppp_pcb *pcb, u8_t authtype, const char *user, const char *passwd);
  
  /*
   * If set, peer is required to authenticate. This is mostly necessary for PPP server support.
   *
   * Default is false.
   */
  #define ppp_set_auth_required(ppp, boolval) (ppp->settings.auth_required = boolval)
  #endif /* PPP_AUTH_SUPPORT */
  
  #if PPP_IPV4_SUPPORT
  /*
   * Set PPP interface "our" and "his" IPv4 addresses. This is mostly necessary for PPP server
   * support but it can also be used on a PPP link where each side choose its own IP address.
   *
   * Default is unset (0.0.0.0).
   */
  #define ppp_set_ipcp_ouraddr(ppp, addr) do { ppp->ipcp_wantoptions.ouraddr = ip4_addr_get_u32(addr); \
                                               ppp->ask_for_local = ppp->ipcp_wantoptions.ouraddr != 0; } while(0)
  #define ppp_set_ipcp_hisaddr(ppp, addr) (ppp->ipcp_wantoptions.hisaddr = ip4_addr_get_u32(addr))
  #if LWIP_DNS
  /*
   * Set DNS server addresses that are sent if the peer asks for them. This is mostly necessary
   * for PPP server support.
   *
   * Default is unset (0.0.0.0).
   */
  #define ppp_set_ipcp_dnsaddr(ppp, index, addr) (ppp->ipcp_allowoptions.dnsaddr[index] = ip4_addr_get_u32(addr))
  
  /*
   * If set, we ask the peer for up to 2 DNS server addresses. Received DNS server addresses are
   * registered using the dns_setserver() function.
   *
   * Default is false.
   */
  #define ppp_set_usepeerdns(ppp, boolval) (ppp->settings.usepeerdns = boolval)
  #endif /* LWIP_DNS */
  #endif /* PPP_IPV4_SUPPORT */
  
  #if MPPE_SUPPORT
  /* Disable MPPE (Microsoft Point to Point Encryption). This parameter is exclusive. */
  #define PPP_MPPE_DISABLE           0x00
  /* Require the use of MPPE (Microsoft Point to Point Encryption). */
  #define PPP_MPPE_ENABLE            0x01
  /* Allow MPPE to use stateful mode. Stateless mode is still attempted first. */
  #define PPP_MPPE_ALLOW_STATEFUL    0x02
  /* Refuse the use of MPPE with 40-bit encryption. Conflict with PPP_MPPE_REFUSE_128. */
  #define PPP_MPPE_REFUSE_40         0x04
  /* Refuse the use of MPPE with 128-bit encryption. Conflict with PPP_MPPE_REFUSE_40. */
  #define PPP_MPPE_REFUSE_128        0x08
  /*
   * Set MPPE configuration
   *
   * Default is disabled.
   */
  void ppp_set_mppe(ppp_pcb *pcb, u8_t flags);
  #endif /* MPPE_SUPPORT */
  
  /*
   * Wait for up to intval milliseconds for a valid PPP packet from the peer.
   * At the end of this  time, or when a valid PPP packet is received from the
   * peer, we commence negotiation by sending our first LCP packet.
   *
   * Default is 0.
   */
  #define ppp_set_listen_time(ppp, intval) (ppp->settings.listen_time = intval)
  
  /*
   * If set, we will attempt to initiate a connection but if no reply is received from
   * the peer, we will then just wait passively for a valid LCP packet from the peer.
   *
   * Default is false.
   */
  #define ppp_set_passive(ppp, boolval) (ppp->lcp_wantoptions.passive = boolval)
  
  /*
   * If set, we will not transmit LCP packets to initiate a connection until a valid
   * LCP packet is received from the peer. This is what we usually call the server mode.
   *
   * Default is false.
   */
  #define ppp_set_silent(ppp, boolval) (ppp->lcp_wantoptions.silent = boolval)
  
  /*
   * If set, enable protocol field compression negotiation in both the receive and
   * the transmit direction.
   *
   * Default is true.
   */
  #define ppp_set_neg_pcomp(ppp, boolval) (ppp->lcp_wantoptions.neg_pcompression = \
                                           ppp->lcp_allowoptions.neg_pcompression = boolval)
  
  /*
   * If set, enable Address/Control compression in both the receive and the transmit
   * direction.
   *
   * Default is true.
   */
  #define ppp_set_neg_accomp(ppp, boolval) (ppp->lcp_wantoptions.neg_accompression = \
                                            ppp->lcp_allowoptions.neg_accompression = boolval)
  
  /*
   * If set, enable asyncmap negotiation. Otherwise forcing all control characters to
   * be escaped for both the transmit and the receive direction.
   *
   * Default is true.
   */
  #define ppp_set_neg_asyncmap(ppp, boolval) (ppp->lcp_wantoptions.neg_asyncmap = \
                                              ppp->lcp_allowoptions.neg_asyncmap = boolval)
  
  /*
   * This option sets the Async-Control-Character-Map (ACCM) for this end of the link.
   * The ACCM is a set of 32 bits, one for each of the ASCII control characters with
   * values from 0 to 31, where a 1 bit  indicates that the corresponding control
   * character should not be used in PPP packets sent to this system. The map is
   * an unsigned 32 bits integer where the least significant bit (00000001) represents
   * character 0 and the most significant bit (80000000) represents character 31.
   * We will then ask the peer to send these characters as a 2-byte escape sequence.
   *
   * Default is 0.
   */
  #define ppp_set_asyncmap(ppp, intval) (ppp->lcp_wantoptions.asyncmap = intval)
  
  /*
   * Set a PPP interface as the default network interface
   * (used to output all packets for which no specific route is found).
   */
  #define ppp_set_default(ppp)         netif_set_default(ppp->netif)
  
  #if PPP_NOTIFY_PHASE
  /*
   * Set a PPP notify phase callback.
   *
   * This can be used for example to set a LED pattern depending on the
   * current phase of the PPP session.
   */
  typedef void (*ppp_notify_phase_cb_fn)(ppp_pcb *pcb, u8_t phase, void *ctx);
  void ppp_set_notify_phase_callback(ppp_pcb *pcb, ppp_notify_phase_cb_fn notify_phase_cb);
  #endif /* PPP_NOTIFY_PHASE */
  
  /*
   * Initiate a PPP connection.
   *
   * This can only be called if PPP is in the dead phase.
   *
   * Holdoff is the time to wait (in seconds) before initiating
   * the connection.
   *
   * If this port connects to a modem, the modem connection must be
   * established before calling this.
   */
  err_t ppp_connect(ppp_pcb *pcb, u16_t holdoff);
  
  #if PPP_SERVER
  /*
   * Listen for an incoming PPP connection.
   *
   * This can only be called if PPP is in the dead phase.
   *
   * If this port connects to a modem, the modem connection must be
   * established before calling this.
   */
  err_t ppp_listen(ppp_pcb *pcb);
  #endif /* PPP_SERVER */
  
  /*
   * Initiate the end of a PPP connection.
   * Any outstanding packets in the queues are dropped.
   *
   * Setting nocarrier to 1 close the PPP connection without initiating the
   * shutdown procedure. Always using nocarrier = 0 is still recommended,
   * this is going to take a little longer time if your link is down, but
   * is a safer choice for the PPP state machine.
   *
   * Return 0 on success, an error code on failure.
   */
  err_t ppp_close(ppp_pcb *pcb, u8_t nocarrier);
  
  /*
   * Release the control block.
   *
   * This can only be called if PPP is in the dead phase.
   *
   * You must use ppp_close() before if you wish to terminate
   * an established PPP session.
   *
   * Return 0 on success, an error code on failure.
   */
  err_t ppp_free(ppp_pcb *pcb);
  
  /*
   * PPP IOCTL commands.
   *
   * Get the up status - 0 for down, non-zero for up.  The argument must
   * point to an int.
   */
  #define PPPCTLG_UPSTATUS 0
  
  /*
   * Get the PPP error code.  The argument must point to an int.
   * Returns a PPPERR_* value.
   */
  #define PPPCTLG_ERRCODE  1
  
  /*
   * Get the fd associated with a PPP over serial
   */
  #define PPPCTLG_FD       2
  
  /*
   * Get and set parameters for the given connection.
   * Return 0 on success, an error code on failure.
   */
  err_t ppp_ioctl(ppp_pcb *pcb, u8_t cmd, void *arg);
  
  /* Get the PPP netif interface */
  #define ppp_netif(ppp)               (ppp->netif)
  
  /* Set an lwIP-style status-callback for the selected PPP device */
  #define ppp_set_netif_statuscallback(ppp, status_cb)       \
          netif_set_status_callback(ppp->netif, status_cb);
  
  /* Set an lwIP-style link-callback for the selected PPP device */
  #define ppp_set_netif_linkcallback(ppp, link_cb)           \
          netif_set_link_callback(ppp->netif, link_cb);
  
  #ifdef __cplusplus
  }
  #endif
  
  #endif /* PPP_H */
  
  #endif /* PPP_SUPPORT */
  